Composite structures comprising an adhesive blend and one or more substrates, especially polar substrates, are finding great utility in industry. Examples of polar substrates are nylon, ethylene-vinyl alcohol copolymers (EVOH), polyvinyl alcohol polymers (PVOH), metals, glass and wood.
Adhesive blends of polyolefins (either homopolymer or copolymer) with graft copolymers of unsaturated carboxylic acids and their derivatives such as anhydrides, esters, amides, imides, metal salts, and the like, and the resulting composite structures, are finding increasing uses. The improvement of this invention includes preparing the graft copolymer with a linear low density polyethylene (LLDPE) backbone instead of a high density polyethylene or low density polyethylene backbone.
This invention permits reducing the temperature for the onset of adhesion of polyolefin adhesive blends compared to that for blends containing high-density polyethylene graft copolymer, by substituting in its place a linear low density polyethylene graft copolymer.
This invention also provides new adhesive blends with improved adhesion over blends containing conventional branched low density polyethylene graft copolymers. These adhesive blends show good adhesion to olefin polymers as well as to other substrates such as nylons, polyamides, polyvinyl alcohol and its copolymers including ethylene-vinyl alcohol copolymers, polyurethanes, polyesters, aluminum, steel, copper and other metals, paper, wood, leather, polycarbonates and the like.
The invention also includes composite structures including the adhesive blends of this invention. The composite structure can be in the form of films, containers, sheets, bottles, tubes, etc.
This invention includes any process or method that uses these blends for combining dissimilar materials. Examples of such processes are lamination, coextrusion, blow molding, extrusion coating, powder coating, etc., or any combination thereof.